PROJECT SUMMARY/ABSTRACT Immunosuppressive (IS) medication nonadherence is a health management problem with dire consequences for solid organ transplant (SOT) recipients, placing them at increased risk for hospitalization (1,2), rejection (2?4), graft loss, and mortality (1,4?6). The risk for nonadherence peaks in adolescence (7?10), making this developmental stage a critical time for intervention. Significant research efforts have been made to improve adherence; yet, published interventions have generally not demonstrated improved clinical outcomes (11). To address this gap, this application proposes a secondary analysis of data collected through the multi- site Clinical Trials in Organ Transplantation in Children consortium?s Protocol 11 (CTOT-C-11): ?Prevalence & Correlates of Post-Traumatic Stress Symptoms (PTSS) in Adolescent Solid Organ Transplant Recipients.? CTOT-C-11 is the largest currently established cohort of adolescent SOT recipients. The primary aim of the proposed study is to compare demographic and psychosocial profiles of adherent (A), mildly nonadherent (MA), and severely nonadherent (SA) adolescent SOT recipients and identify patterns of risk to create a targeted adherence intervention and treatment manual. Adherence will be measured using the Medication Level Variability Index (MLVI), a robust biomarker of IS adherence. It is hypothesized that patient/transplant characteristics (PTSS, depressive symptoms, sex, age, transplant type, insurance status) and parental factors (PTSS, education, marital status) will have differential associations and interconnections with the adherence levels (A, MA, SA). It is also hypothesized that degree of symptom severity or characteristic level will predict patients? adherence class (e.g. MA patients will have higher PTSS compared to A patients, but lower PTSS compared to SA patients). Exploratory analyses will investigate how the profiles of A, MA, and SA patients are related to transplant outcomes (i.e. rejection/graft failure as defined by CTOT-C-11). This project will culminate in the development of an intervention and treatment manual designed to improve IS adherence. The analyses described in the primary aim will be used to target the intervention components to specific levels of adherence (A, MA, and SA) ? an approach that has not been tried in this population. This proposed project seeks to advance the understanding of nonadherence behavior in order to strengthen the interventions available to clinicians and thereby promote the health of SOT recipients and chronically ill populations more broadly. The proposed fellowship training plan would provide the applicant in-depth training in correspondence analysis [an advanced statistical method for categorical data (12)], intervention development, and treatment manual writing. This training will take place at Fordham University, a research institution in New York City, and Icahn School of Medicine at Mount Sinai, an academic medical teaching facility also in NYC. Both will provide substantial support for the proposed training activities as well as professional development opportunities to prepare the applicant to become a successful contributor to intervention science and behavioral health.